The disaster in NO was largely thanks to the US Army Corps of Engineers and their attempts to tame the Mississipi and Atchafalaya rivers over the past half century or so. NO is built on silt deposits that compact over time; these are layed down by the normal flooding activity. However, since we prefer not to have our major cities flooded every year, the levees were built to keep NO generally drier and less prone to floods. Great idea in theory, except that this prevents the floods from depositing more silt, so the land that the city is built upon just sinks instead of getting new earth to be on top of. Worse, the silt that would have been deposited all over the delta is instead deposited in the channel; this builds up (just like at the base of a dam), which displaces more and more of the water, meaning that you have to keep making your levee taller and taller, leading eventually to having a large amount of water suspended significantly higher than the inhabited land around it; this has the nice bonus of increasing the potential energy of anything that might happen to break through or spill over the top of your levee. Just like a dammed river will eventually cut a path through the dam, nature will eventually win and your levee will fail; this was pretty much an inevitable certainty without Katrina, but extreme weather conditions vastly accelerated the issue. The result is a new Atlantis.
But it's even worse than that -- NO is not going to be viable long-term anyway, because as the Corps of Engineers has attempted to tame Mother Nature in the Mississipi Delta, they have caused the Mississipi to change course; the river's new preferred course will take it quite a ways away from all of the economic infrastructure that depends on being at the mouth of the river. D'oh!
John McPhee's The Control of Nature (http://www.amazon.com/exec/obidos/tg/detail/-/0374522596/qid=1125598027/sr=1-1/ref=sr_1_1/103-2228170-9851029?v=glance&s=books) is strongly recommended reading and explains the situation much better than my little summary. (It's been about 12 years since I read it, so I'm a little fuzzy on some of the specifics.) In fact, all of his work is fairly excellent, from what I recall.
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Date: 2005-09-01 06:08 pm (UTC)But it's even worse than that -- NO is not going to be viable long-term anyway, because as the Corps of Engineers has attempted to tame Mother Nature in the Mississipi Delta, they have caused the Mississipi to change course; the river's new preferred course will take it quite a ways away from all of the economic infrastructure that depends on being at the mouth of the river. D'oh!
John McPhee's The Control of Nature (http://www.amazon.com/exec/obidos/tg/detail/-/0374522596/qid=1125598027/sr=1-1/ref=sr_1_1/103-2228170-9851029?v=glance&s=books) is strongly recommended reading and explains the situation much better than my little summary. (It's been about 12 years since I read it, so I'm a little fuzzy on some of the specifics.) In fact, all of his work is fairly excellent, from what I recall.